When rolling an annular workpiece to shape the workpiece is rotatably supported on a mandrel. The mandrel can be in the form of a metal shaft onto which an annular workpiece is slid before rolling starts. The diameter of the mandrel is such that it allows the workpiece to slide freely onto the mandrel, but, as soon as the rolls are rotated and moved towards each other they squeeze the workpiece between themselves and the mandrel and the workpiece is forced into contact with the mandrel so causing the two to rotate together.
One of the drawbacks with this system is that only the outer surface of the workpiece can be formed in a single operation. The forming of the side chamfers must be carried out in a further machining operation. Also some form of opposed springs are needed to locate the workpiece accurately on the mandrel.